diff --git a/EDAC/RS/ReedSolomonAlgorithm.cs b/EDAC/RS/ReedSolomonAlgorithm.cs new file mode 100644 index 0000000..df3920e --- /dev/null +++ b/EDAC/RS/ReedSolomonAlgorithm.cs @@ -0,0 +1,95 @@ +/** +* Digital Voice Modem - Fixed Network Equipment +* AGPLv3 Open Source. Use is subject to license terms. +* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. +* +* @package DVM / Fixed Network Equipment +* +*/ +/* +* This program is free software: you can redistribute it and/or modify +* it under the terms of the GNU Affero General Public License as published by +* the Free Software Foundation, either version 3 of the License, or +* (at your option) any later version. +* +* This program is distributed in the hope that it will be useful, +* but WITHOUT ANY WARRANTY; without even the implied warranty of +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +* GNU Affero General Public License for more details. +*/ + +using System; + +namespace fnecore.EDAC.RS +{ + /// + /// + /// + public enum ErrorCorrectionCodeType + { + /// + /// (63,47,17) + /// + ReedSolomon_634717, + /// + /// (24,12,13) + /// + ReedSolomon_241213, + /// + /// (24,16,9) + /// + ReedSolomon_24169 + } // public enum ErrorCorrectionCodeType + + /// + /// + /// + public static class ReedSolomonAlgorithm + { + /* + ** Methods + */ + + /// + /// Produces error correction codewords for a message using the Reed-Solomon algorithm. + /// + /// The message to compute the error correction codewords. + /// The type of Galois field to use to encode error correction codewords. + /// Returns the computed message with error correction codewords. + public static byte[] Encode(byte[] message, ErrorCorrectionCodeType eccType) + { + ReedSolomonEncoder reedSolomonEncoder = new ReedSolomonEncoder(); + byte[] output = new byte[message.Length]; + Buffer.BlockCopy(message, 0, output, 0, message.Length); + + if (eccType == ErrorCorrectionCodeType.ReedSolomon_634717) + { + reedSolomonEncoder.encode362017(ref output); + return output; + } + else if (eccType == ErrorCorrectionCodeType.ReedSolomon_241213) + { + reedSolomonEncoder.encode241213(ref output); + return output; + } + else if (eccType == ErrorCorrectionCodeType.ReedSolomon_24169) + { + reedSolomonEncoder.encode24169(ref output); + return output; + } + else + throw new ArgumentException($"Invalid '{nameof(eccType)}' argument.", nameof(eccType)); + } + + /// + /// Repairs a possibly broken message using the Reed-Solomon algorithm. + /// + /// The possibly broken message to repair. + /// The type of Galois field to use to decode message. + /// Returns the repaired message, or null if it cannot be repaired. + public static byte[] Decode(byte[] message, ErrorCorrectionCodeType eccType) + { + throw new NotImplementedException(); + } + } // public static class ReedSolomonAlgorithm +} // namespace fnecore.EDAC.RS diff --git a/EDAC/RS/ReedSolomonEncoder.cs b/EDAC/RS/ReedSolomonEncoder.cs new file mode 100644 index 0000000..91d8408 --- /dev/null +++ b/EDAC/RS/ReedSolomonEncoder.cs @@ -0,0 +1,249 @@ +/** +* Digital Voice Modem - Fixed Network Equipment +* AGPLv3 Open Source. Use is subject to license terms. +* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. +* +* @package DVM / Fixed Network Equipment +* +*/ +// +// Based on code from the MMDVMHost project. (https://github.com/g4klx/MMDVMHost) +// Licensed under the GPLv2 License (https://opensource.org/licenses/GPL-2.0) +// +/* +* Copyright (C) 2016 by Jonathan Naylor G4KLX +* Copyright (C) 2017-2023 by Bryan Biedenkapp N2PLL +* +* This program is free software; you can redistribute it and/or modify +* it under the terms of the GNU General Public License as published by +* the Free Software Foundation; either version 2 of the License, or +* (at your option) any later version. +* +* This program is distributed in the hope that it will be useful, +* but WITHOUT ANY WARRANTY; without even the implied warranty of +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +* GNU General Public License for more details. +* +* You should have received a copy of the GNU General Public License +* along with this program; if not, write to the Free Software +* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. +*/ + +using System; + +namespace fnecore.EDAC.RS +{ + /// + /// Implements Reed-Solomon encoding, as the name implies. + /// + internal sealed class ReedSolomonEncoder + { + private static readonly byte[][] ENCODE_MATRIX = new byte[12][] { + new byte[24] { 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 062, 044, 003, 025, 014, 016, 027, 003, 053, 004, 036, 047 }, + new byte[24] { 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 011, 012, 011, 011, 016, 064, 067, 055, 001, 076, 026, 073 }, + new byte[24] { 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 003, 001, 005, 075, 014, 006, 020, 044, 066, 006, 070, 066 }, + new byte[24] { 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 021, 070, 027, 045, 016, 067, 023, 064, 073, 033, 044, 021 }, + new byte[24] { 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 030, 022, 003, 075, 015, 015, 033, 015, 051, 003, 053, 050 }, + new byte[24] { 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 001, 041, 027, 056, 076, 064, 021, 053, 004, 025, 001, 012 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 061, 076, 021, 055, 076, 001, 063, 035, 030, 013, 064, 070 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 024, 022, 071, 056, 021, 035, 073, 042, 057, 074, 043, 076 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 072, 042, 005, 020, 043, 047, 033, 056, 001, 016, 013, 076 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 072, 014, 065, 054, 035, 025, 041, 016, 015, 040, 071, 026 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 073, 065, 036, 061, 042, 022, 017, 004, 044, 020, 025, 005 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 071, 005, 055, 003, 071, 034, 060, 011, 074, 002, 041, 050 } + }; + + private static readonly byte[][] ENCODE_MATRIX_24169 = new byte[16][] { + new byte[24] { 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 051, 045, 067, 015, 064, 067, 052, 012 }, + new byte[24] { 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 057, 025, 063, 073, 071, 022, 040, 015 }, + new byte[24] { 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 005, 001, 031, 004, 016, 054, 025, 076 }, + new byte[24] { 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 073, 007, 047, 014, 041, 077, 047, 011 }, + new byte[24] { 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 075, 015, 051, 051, 017, 067, 017, 057 }, + new byte[24] { 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 020, 032, 014, 042, 075, 042, 070, 054 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 002, 075, 043, 005, 001, 040, 012, 064 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 024, 074, 015, 072, 024, 026, 074, 061 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 042, 064, 007, 022, 061, 020, 040, 065 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 032, 032, 055, 041, 057, 066, 021, 077 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 065, 036, 025, 007, 050, 016, 040, 051 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 064, 006, 054, 032, 076, 046, 014, 036 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 062, 063, 074, 070, 005, 027, 037, 046 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 055, 043, 034, 071, 057, 076, 050, 064 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 024, 023, 023, 005, 050, 070, 042, 023 }, + new byte[24] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 067, 075, 045, 060, 057, 024, 006, 026 } + }; + + private static readonly byte[][] ENCODE_MATRIX_362017 = new byte[20][] { + new byte[36] { 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 074, 037, 034, 006, 002, 007, 044, 064, 026, 014, 026, 044, 054, 013, 077, 005 }, + new byte[36] { 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 004, 017, 050, 024, 011, 005, 030, 057, 033, 003, 002, 002, 015, 016, 025, 026 }, + new byte[36] { 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 007, 023, 037, 046, 056, 075, 043, 045, 055, 021, 050, 031, 045, 027, 071, 062 }, + new byte[36] { 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 026, 005, 007, 063, 063, 027, 063, 040, 006, 004, 040, 045, 047, 030, 075, 007 }, + new byte[36] { 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 023, 073, 073, 041, 072, 034, 021, 051, 067, 016, 031, 074, 011, 021, 012, 021 }, + new byte[36] { 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 024, 051, 025, 023, 022, 041, 074, 066, 074, 065, 070, 036, 067, 045, 064, 001 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 052, 033, 014, 002, 020, 006, 014, 025, 052, 023, 035, 074, 075, 075, 043, 027 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 055, 062, 056, 025, 073, 060, 015, 030, 013, 017, 020, 002, 070, 055, 014, 047 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 054, 051, 032, 065, 077, 012, 054, 013, 035, 032, 056, 012, 075, 001, 072, 063 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 074, 041, 030, 041, 043, 022, 051, 006, 064, 033, 003, 047, 027, 012, 055, 047 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 054, 070, 011, 003, 013, 022, 016, 057, 003, 045, 072, 031, 030, 056, 035, 022 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 051, 007, 072, 030, 065, 054, 006, 021, 036, 063, 050, 061, 064, 052, 001, 060 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 001, 065, 032, 070, 013, 044, 073, 024, 012, 052, 021, 055, 012, 035, 014, 072 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 011, 070, 005, 010, 065, 024, 015, 077, 022, 024, 024, 074, 007, 044, 007, 046 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 006, 002, 065, 011, 041, 020, 045, 042, 046, 054, 035, 012, 040, 064, 065, 033 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 034, 031, 001, 015, 044, 064, 016, 024, 052, 016, 006, 062, 020, 013, 055, 057 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 063, 043, 025, 044, 077, 063, 017, 017, 064, 014, 040, 074, 031, 072, 054, 006 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 071, 021, 070, 044, 056, 004, 030, 074, 004, 023, 071, 070, 063, 045, 056, 043 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 002, 001, 053, 074, 002, 014, 052, 074, 012, 057, 024, 063, 015, 042, 052, 033 }, + new byte[36] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 034, 035, 002, 023, 021, 027, 022, 033, 064, 042, 005, 073, 051, 046, 073, 060 } + }; + + /* + ** Methods + */ + + /// + /// Encode RS (24,12,13) FEC. + /// + /// Raw data to encode with Reed-Solomon FEC. + public void encode241213(ref byte[] data) + { + if (data == null) + throw new NullReferenceException(); + + byte[] codeword = new byte[24U]; + + for (uint i = 0U; i < 24U; i++) + { + codeword[i] = 0x00; + + uint offs = 0U; + for (uint j = 0U; j < 12U; j++, offs += 6U) + { + byte hexbit = bin2Hex(data, offs); + codeword[i] ^= gf6Mult(hexbit, ENCODE_MATRIX[j][i]); + } + } + + uint offset = 0U; + for (uint i = 0U; i < 24U; i++, offset += 6U) + hex2Bin(codeword[i], ref data, offset); + } + + /// + /// Encode RS (24,16,9) FEC. + /// + /// Raw data to encode with Reed-Solomon FEC. + public void encode24169(ref byte[] data) + { + if (data == null) + throw new NullReferenceException(); + + byte[] codeword = new byte[24U]; + + for (uint i = 0U; i < 24U; i++) + { + codeword[i] = 0x00; + + uint offs = 0U; + for (uint j = 0U; j < 16U; j++, offs += 6U) + { + byte hexbit = bin2Hex(data, offs); + codeword[i] ^= gf6Mult(hexbit, ENCODE_MATRIX_24169[j][i]); + } + } + + uint offset = 0U; + for (uint i = 0U; i < 24U; i++, offset += 6U) + hex2Bin(codeword[i], ref data, offset); + } + + /// + /// Encode RS (36,20,17) FEC. + /// + /// Raw data to encode with Reed-Solomon FEC. + public void encode362017(ref byte[] data) + { + if (data == null) + throw new NullReferenceException(); + + byte[] codeword = new byte[36U]; + + for (uint i = 0U; i < 36U; i++) + { + codeword[i] = 0x00; + + uint offs = 0U; + for (uint j = 0U; j < 20U; j++, offs += 6U) + { + byte hexbit = bin2Hex(data, offs); + codeword[i] ^= gf6Mult(hexbit, ENCODE_MATRIX_362017[j][i]); + } + } + + uint offset = 0U; + for (uint i = 0U; i < 36U; i++, offset += 6U) + hex2Bin(codeword[i], ref data, offset); + } + + /// + /// + /// + /// + /// + /// + private byte bin2Hex(byte[] input, uint offset) + { + byte output = 0x00; + + output |= (byte)(FneUtils.ReadBit(input, offset + 0U) ? 0x20U : 0x00U); + output |= (byte)(FneUtils.ReadBit(input, offset + 1U) ? 0x10U : 0x00U); + output |= (byte)(FneUtils.ReadBit(input, offset + 2U) ? 0x08U : 0x00U); + output |= (byte)(FneUtils.ReadBit(input, offset + 3U) ? 0x04U : 0x00U); + output |= (byte)(FneUtils.ReadBit(input, offset + 4U) ? 0x02U : 0x00U); + output |= (byte)(FneUtils.ReadBit(input, offset + 5U) ? 0x01U : 0x00U); + + return output; + } + + /// + /// + /// + /// + /// + /// + /// + private void hex2Bin(byte input, ref byte[] output, uint offset) + { + FneUtils.WriteBit(ref output, offset + 0U, (input & 0x20U) == 0x20U); + FneUtils.WriteBit(ref output, offset + 1U, (input & 0x10U) == 0x10U); + FneUtils.WriteBit(ref output, offset + 2U, (input & 0x08U) == 0x08U); + FneUtils.WriteBit(ref output, offset + 3U, (input & 0x04U) == 0x04U); + FneUtils.WriteBit(ref output, offset + 4U, (input & 0x02U) == 0x02U); + FneUtils.WriteBit(ref output, offset + 5U, (input & 0x01U) == 0x01U); + } + + /// + /// + /// + /// GF(2 ^ 6) multiply (for Reed-Solomon encoder). + /// + /// + /// + private byte gf6Mult(byte a, byte b) + { + byte p = 0x00; + + for (uint i = 0U; i < 6U; i++) { + if ((b & 0x01) == 0x01) + p ^= a; + + a <<= 1; + + if ((a & 0x40) == 0x40) + a ^= 0x43; // primitive polynomial : x ^ 6 + x + 1 + + b >>= 1; + } + + return p; + } + } // internal sealed class ReedSolomonEncoder +} // namespace fnecore.EDAC.RS